How To Gel Coat A Sailboat - A Complete Guide

How To Gel Coat A Sailboat | Life of Sailing

Last Updated by

Daniel Wade

June 15, 2022

Although gel coating your sailboat won’t make it catch more fish or sail any better, it makes your sailboat attractive, will reinforce your pride and joy, and more importantly, it will protect your boat from external elements. With the rights tools, you can apply a gel coat to your boat without necessarily hiring a professional and this will allow you to save money.

If you’ve been out there on a sail, you’ll instantaneously agree that sailing is a life’s pleasure that most landlubbers will never come to terms with. For those of us who own boats, it’s the only realistic way of life. Whether you are the proud owner of a 25ft fishing boat or have a 40ft personal watercraft, you certainly know the importance of refurbishing and gel coating your boat. In addition to protecting your boat against the elements, gel coating your boat will make it seaworthy and you’ll turn heads while out there on the water.

The process of gel coating a boat is easier than most boat owners think. Given that many boats utilize fiberglass in their construction, gel coating a boat is the only way to make it bright and shiny while also protecting it against the elements. As such, the process involves removing all the surface dirt by thoroughly cleaning the boat, removing the stains, removing the oxidation and restoring the shine, and protecting the shine with wax.

This article, therefore, walks you through how to gel coat a sailboat without seeking the services of a professional.


Table of contents

What is Gel Coat?

A gel coat is technically a surface coating of pigmented polyester resin that perfectly gels with any structural fiberglass not just to cure it of any mold surfaces but also to produce a smooth, glossy, and durable surface. Given that most boats are made of fiberglass exterior, a gel coat can help in imparting color, protecting the fiberglass from external elements, thereby preventing a boat’s hull and the exterior surface from decaying or weakening as a result of water and ultraviolet light intrusion. A gel coat can also protect the boat from leaks and cracks.

With that in mind, it’s of great importance for every boat owner to at least know how to apply a gel coat to a boat. Fortunately, this complete guide walks you through the entire process.

How to Apply Gel Coat to a Boat

1) Getting Ready

As we noted earlier, achieving a perfect gel coat largely depends on the preparation you put in place. In addition to having the right tools, you should have all the supplies ready ahead of time. Well, it would be a waste of time and effort to do a store run in the middle of a paint job. Again, you have to keep in mind that it’s almost impossible to apply the gel coat on the water. This means that you need to find a shaded and well-ventilated workspace. You should gel coat your boat in extreme weather conditions such as when it raining or when it’s hot as this can hugely affect the repair.

That being said, here are the items you need to gel coat your sailboat.

  • Boat fiberglass cleaning solution
  • Pressure spray hose
  • Acetone solution
  • Bucket
  • Masking tape
  • Large rags and sponges
  • Microfiber cloth
  • Safety goggles
  • Disposable gloves
  • Disposable masks
  • Spray coat applicator
  • Paintbrush
  • Sealant
  • Fine-grain sandpaper
  • Gel coat paste
  • Wax paper or plastic film
  • Fiberglass filler
  • Spray or liquid gel coat
  • Fiberglass hardener
  • Fiberglass filler
  • Buffing machine
  • Rubbing compound
  • Wax
  • Polish

2) Clean Your Boat Thoroughly

It’s essential that you thoroughly clean your boat to remove all the surface dirt using an appropriate boat cleaning product. For instance, you can use a marine boat soap, which has a low-siding formula meant for the marine environment. You should avoid using typical dishwashing liquids as they are generally high in sulfonates and this can be damage your boat further.

If the boat has molded-in non-skid areas, which are difficult to clean, you can use chelating non-skid cleaner. Such products are specifically formulated to easily break the bond between the dirt and the exterior of your boat. In other words, you won’t have to heavily scrub your boat a chelated non-skid cleaner.

You should then thoroughly rinse the boat with a pressurized spray hose to make sure that any remaining dirt is removed. The idea here is that your gel coat won’t stick if there’s dirt on your boat. You shouldn’t forget to meticulously wipe dry the boat with a clean microfiber cloth.

3) Inspect the Boat for any Damage

Now that you’ve thoroughly cleaned the boat, it’s significant that you inspect the boat for any form of damage, crack, scratch, chip or worn out surface. Check around stanchions or other areas that indicate an underlying structural issue.

You should cover these surfaces using the painter’s tape or masking tape. If you want to repair these damaged areas, you should wet sand the damages with medium-grit sandpaper. You should make sure that the sandpaper is of the right grit to avoid damaging a perfect gel coat layer.

4) Remove Stains

Unless your boat is brand new, it will have some degree of stain. But because it’s impossible to remove all the stains that exist at a deeper level within the permeable gel coat surface, it would be a very bad idea to use typical soap and water. If anything, soap and water will not perfectly remove mineral stains (such as black streaks and rust stains) and/or organic stains (such as coffee and spillage, bird dropping or discoloration caused by falling leaves).

As such, the best way to remove these stains is by using acid-based stain removers that come in the form of a gel. This is because they’re a lot easier to use and hold well in vertical boat surfaces. You should make sure that you wear the goggles and facemask to protect your face and eyes and rubber gloves to protect your hands. You should also make sure that the acid-based stain removes do not spill on other parts of the boat as it may damage the paint, varnish or dull your boat.

If you have trouble using an acid-based remover for any apparent reason, you can consider specific stain removers that are particularly formulated for a given job. For instance, you can use bird dropping stain removers to remove bird droppings or rust stain removers to remove rust stains.

5) Remove the Oxidation and Restore the Shine

Unless your boat is brand new, it has some oxidation that must be removed as it is what makes the gel coat dull. In most cases, light oxidation makes your boat slightly dull while heavy oxidation gives your boat’s gel coat a heavy chalk-like powder look.

If your boat is heavily oxidized (has a chalk-like powder look), you should first use a rubbing compound that uses abrasives to smooth remove the oxidation and restore the original shine. You can then follow up with a finer grade of polish. You should, however, keep in mind that this process does remove a given level of gel coat. For this reason, you should use the least aggressive product that will get the job done. Even though you can apply these products by hand; using a machine will work much better.

6) Apply the Gel Coat Paste

You’ve probably been looking forward to this step and here we are. But before applying the gel coat paste, make sure that you match the pigment of the gel coat paste with the hue of your boat’s hull. You should carry out a test to get the perfect gel coat paint. Once you’ve obtained the right gel coat color, make sure that you remove the masking tapes and use a putty knife to apply the gel coat paste in the damaged areas.

Make sure that there are no air bubbles that might want to escape once you’ve applied the gel coat paste. You should then let the gel coat paste to perfectly cure the areas before covering the treated areas with wax paper or plastic film. You shouldn’t rush things. You can even re-sand the area and apply another coating of the gel coat paste to make it durable before allowing it to dry.

You can then apply the fiberglass cleaner to restore the shine and remove any remaining dirt residue. You should also fill the damaged areas with a mix of fiberglass filler and hardener and make sure that it blends well with the gel coat.

7) Wax the Boat to Protect the Shine

Once you’ve removed the stains and polished the surface, you should seal and protect the surface with wax. This is to prevent oxygen to permeate the gel coat and cause oxidation. Many waxes contain inhibitors that are specifically formulated to protect the gel coat against various elements. Make sure that you do not apply the wax under direct sunlight.

It’s important to note that gel coat polishing and waxing should always be carried out as very separate operations. Like waxing, you can polish your boat either by hand or using a machine though machines always work better. There are two types of polishing machines: variable speed circular polishers and random orbital polishers. The former can be great for pros looking to cover a lot of ground within a very short period while the latter is perfect for novices.


We all know the importance of a gel coat in giving your boat a shiny gloss while out there on the water. In addition to protecting your boat from the elements, it will make your boat attractive and turn heads. Fortunately, the process of applying a gel coat on your sailboat isn’t rocket science. With the above-described steps, you’ll not only restore your boat but will also avoid the costly services of professionals while keeping your boat afloat.

With the right tools, follow the steps, take your time, be patient, and your boat will be the center of attraction. After all, this process is easier than most boat owners think!

How To Gel Coat A Sailboat - A Complete Guide
Daniel Wade

Daniel Wade

I've personally had thousands of questions about sailing and sailboats over the years. As I learn and experience sailing, and the community, I share the answers that work and make sense to me, here on Life of Sailing.

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